This invention relates to the field of condoms which are effective contraceptives and provide reliable protection against sexually transmitted diseases. More particularly, the present invention relates to spermicidally lubricated polyether polyol aliphatic diisocyanate based polyurethane elastomer condoms.
Rubber latex condoms, both dry and lubricated, have been available for many years. Among the advantages of presently available rubber latex condoms are their relative freedom from side effects to either partner, their low cost and their simplicity of use.
However, the rubber latex condoms have disadvantages such as breakage, leakage and slippage, especially in those cases where thinner materials are used in condom production in order to facilitate increased tactile sensation and heat transference. In such cases, the use of thinner condoms may entail a considerable increase in risk since the thinner condoms may not have adequate tensile strength and break force properties which are necessary to withstand the rigors of robust sexual intercourse.
In order to overcome the disadvantages of rubber latex condoms, it has been proposed to produce condoms from polyurethane elastomers which do not suffer from the undesirable film thickness and inherent insulating characteristics which result in inefficient heat transfer and reduction in sensory perception to the user, which are characteristic of natural rubber latex based condoms.
In general, polyurethane elastomers are polymers produced by the reaction of diisocyanates and polymeric di-hydroxy functional alcohols known as polyols. Polyurethane elastomers are regarded as block copolymers. The highly chemically reactive diisocyanates join the polyols together with a urethane linkage.
Polyols used to form polyurethane elastomers are obtained from two chemically distinct classes: polyether polyols and polyester polyols, the latter including polycaprolactones. For elastomer synthesis, both polyols are available in various molecular weights; products in the 600 to 3000 molecular weight range are commonly used industrially.
The most commonly used polyether polyols are the polypropylene glycols and the polytetramethylene glycols. The polyester polyols are prepared by the reaction of dibasic acids (usually adipic acid) with numerous different diols such as ethylene glycol, 1,2-propylene glycol, diethylene glycol, etc. Currently, polyester polyols are more extensively used for polyurethane elastomer production than are the polyether polyols.
The isocyanates used for elastomer production are generally bi-functional. These diisocyanates can be based on either aromatic or aliphatic structural backbones. An example of an aromatic diisocyanate used for elastomer production is 4,4xe2x80x2-diphenylmethane diisocyanate. An example of an aliphatic diisocyanate used for elastomer production is 4,4xe2x80x2-dicyclohexylmethane diisocyanate.
It is well established that strongly ionic solvents, such as alcohols, can quickly disrupt the molecular chain structure of polyurethanes, leading to a rapid fall in physical properties. In fact, many materials, both relatively ionic and non-ionic, can cause similar disruptions due to the varying morphology and chemistry of these polymers.
Nonoxynol-9 is the active agent in most spermicidal products that are available in the United States. These products include condoms, foams, jellies, creams, suppositories, tablets, etc. Two other spermicides approved for use in the United States are octoxynol and Nonoxynol-11. All three materials can be classified as non-ionic ethoxy-based surfactants that kill sperm by destroying the cell membrane. Other surfactant products, including menfegol and benzalkonium chloride, are widely used as spermicides in other parts of the world.
Spermicides are usually used in conjunction with a base which can act as both a sexual lubricant and carrier for the spermicide.
Non-spermicidal condom lubricants, such as silicone fluids, aqueous systems and poly(alkoxy) glycols such as polyethylene glycol mol. wt. 400, available commercially as PEG 400, are currently used extensively throughout the natural rubber latex condom industry and also act as carriers for the spermicide.
In the U.S., Nonoxynol-9 is used almost exclusively in spermicidally lubricated condom products. Therefore, compatibility of Nonoxynol-9 with polyurethanes is essential if a spermicidally lubricated polyurethane condom is to be successfully developed and marketed.